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Thursday, February 16, 2012

First Case of Legionnaire's Disease Caused by Dentist Visit

Doctors on Friday reported the first known case of Legionnaire's disease, a rare infection usually linked to faulty air conditioning and hot-water systems, that was caused by a visit to the dentist.

The case report, published in The Lancet, describes an unnamed 82-year-old woman in Rome who was hospitalised with fever and breathing problems in February 2011.

Swiftly diagnosed with infection by the Legionella pneumophila germ, she died two days later of septic shock despite being given heavy doses of antibiotics.

During the two- to 10-day time it would have taken for the bacteria to incubate, the patient had only left her house twice, both times to attend appointments at the dentist.

Samples of water were taken from the dentist's tap, from the waterline -- the tube that supplies water to tooth scalers and handpieces used by the dentist -- and from the high-pressure pump supplying the waterline itself.

All three sources tested positive for L. pneumophila, but especially in water taken from the pump.

Genetic sequencing found that the germs there matched the bacteria which killed the patient. The bug turned out to be a particularly virulent sub-strain called Benidorm.

After the dentist's dental unit was cleaned with bleach and hydrogen peroxide, it was clear of the pathogen.

This first demonstrated case means that dentists must take even greater care in decontaminating their waterlines in their dental delivery systems.

When I was in private practice I went to the extreme and filtered (with biological filters) all of my water sources, including handpieces (dental drills) and ultrasonic scaling equipment. As a locum tenens dentists now, I note that most dentists do not necessarily take as much care.

And, if something is missed in cleaning a unit, it could have disastrous consequences.

"The case here shows that the disease can be acquired from a dental unit waterline during routine dental treatment. Aerosolised water from high-speed turbine instruments was most likely the source of the infection."

The case report puts down a series of recommendations, including use of filters, continuous circulation of disinfected water and using sterile water instead of tap water.